The present invention relates to the field of IP telephony. More particularly, the invention relates to an apparatus and method for call progress timing measurement in IP telephony.
A telecommunications tester is an automated system used for the testing of telecommunications systems and devices attached to telephone lines. To perform a test, the tester system launches telephone calls to the system or device to be tested in order to exercise certain capabilities and/or validate the proper operation of the system or device by determining the responses to the test call""s sequence of stimulus or inputs.
One capability of a telecommunications tester is found in what is called call progress detection. Call progress detection is the general term used to describe how and when a test call makes it way through a telephone network and is answered by the system or device under test. Call progress detection refers to the detection and determination of things such as dial tone, busy tone, ring-back tone, DTMF digit tones, periods of silence, answer detection, on-hook detection, interactive voice response (IVR) start/end, and the like.
Packet networks, such as the Internet, are increasingly being used in conjunction with traditional circuit-switched networks to process telephone calls. This use of packet networks to process telephone calls is more commonly known as IP telephony. Conventional telecommunications testers have difficulty making call progress timing measurements in IP telephony because with the addition of a packet network information that is involved in a telephone call must be packetized and then de-packetized. This packetization and de-packetization can often cause a loss of information that is vital to the detection of a specific tone, such as a ring-back tone. The loss is due to the fact that a given ring-back tone cannot quite be reproduced exactly after going through the packet network. Other causes of information loss in IP telephony include queuing/de-jittering, packing/unpacking, and turning silence detection on/off.
Accordingly, there is presently a need for a system or process for effectively and accurately measuring call progress timing in IP telephony.
A method consistent with the present invention provides for measuring call setup time in a network comprised of at least two devices. A first device in the network sends a signal to a second device. The first device monitors for a response from the second device and adjusts an answer tone setting for the second device based on the response. After which, the first device calculates an elapsed time between sending the signal and a receipt of the response.
An apparatus consistent with the present invention measures call setup time. The apparatus provides means for sending a signal to a device, means for monitoring for a response from the device, means for adjusting an answer tone setting for the device based on the response, and means for calculating an elapsed time between sending the signal and a receipt of the response.
Another apparatus consistent with the present invention measures call setup time. The apparatus includes a memory having program instructions and a processor responsive to the program instructions. The processor sends a signal to a device, monitors for a response from the device, adjusts an answer tone setting for the device based on the response, and calculates an elapsed time between sending the signal and a receipt of the response.